Emboli filter

ABSTRACT

An emboli filter for deployment in a body lumen to capture emboli entrained in a fluid flowing through the lumen includes a flexible elongated member sized to be passed through the lumen. A filter media is carried on and substantially surrounding the elongated member. The filter media has a first end secured to the elongated member adjacent the distal end. A second end of the filter media has a periphery movable toward and away from the elongated member. Opposing internal surfaces of the filter media define a volume into which emboli may flow through the second end when the periphery is moved away from the elongated member. The emboli are trapped within the volume when the periphery is moved toward the elongated member. An actuator moves the periphery toward and way from the elongated member. The actuator includes a plurality of elastic loops. The loops are biased to an open loop configuration with the loops urging the periphery away from the elongated member. The actuator is adapted to be manipulated by an operator to urge the loops against the bias to a closed position permitting movement of the periphery toward the elongated member without interference from the loops.

I. BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention pertains to a medical apparatus for passage into a bodylumen of a patient. More particularly, this invention pertains to anemboli filter for deployment in a patient's body lumen to capture embolientrained in fluid flowing through the lumen.

2. Description of the Prior Art

There are numerous medical procedures for introducing tools into apatient's body lumen. For example, occlusion treatment tools (such asangioplasty balloon-tipped catheters, stents or ablation catheters) maybe admitted into a lumen of an artery to treat an occluded site withinthe artery. A balloon tipped catheter may be expanded at the site tourge the occlusion against the walls of the artery to improve patency ofthe arterial lumen. A stent may be expanded at the site to maintainlumen patency. Alternatively, or in combination with other procedures,an ablation tool may be used to mechanical remove the occludingmaterial.

The manipulation and use of tools within a lumen of a body passage maycause the release of emboli in the lumen. In arteries, such embolibecome entrained within blood flow within the artery. Such emboli cancontribute to morbidity. For example, emboli can be transported to thebrain and contribute to cranial ischemia (stroke). In treatingocclusions in coronary arteries, emboli may flow to occlude distal,micro-vessels contributing to myocardial ischemia.

In order to reduce morbidity associated with emboli, filters have beendeveloped to capture emboli for removal from the lumen. An example ofsuch a filter is shown in U.S. Pat. No. 5,695,519. Typically, suchfilters include a filter media carried on an elongated, flexible member.The filter media commonly has an open cell construction with a cell ormesh size of 50-300 micrometers (μm) to capture emboli while permittingfluid (e.g., blood) flow past the filter. The filter media is opened andclosed in an umbrella-like fashion. In the open position, the filtermedia substantially fills the cross-section of the body lumen such thatsubstantially all emboli-laden fluid flow must pass through the filtermedia. When closed, the filter media captures the emboli and the filteris reduced in size to pass through the lumen for removal.

Emboli filters should be easy to use and highly flexible to pass throughnarrow vasculature. The filters should open in a manner atraumatic tothe vessel. The filter should open in a manner to accommodate anon-circular cross-section while covering as much as possible of thecross-sectional area of the vessel. Such a filter need not abut the wallof the vessel since fluid flow at the wall is turbulent and emboli-ladenflow is spaced from the wall. Preferably the filter media is highlyflexible and the filter design permits a long filter to enlarge filtervolume.

II. SUMMARY OF THE INVENTION

An emboli filter is disclosed for deployment in a body lumen to captureemboli entrained in a fluid flowing through the lumen. The filterincludes a flexible elongated member sized to be passed through thelumen. A filter media is carried on and substantially surrounds theelongated member. The filter media has a first end secured to theelongated member adjacent the distal end. A second end of the filtermedia has a periphery movable radially toward and away from theelongated member. Opposing internal surfaces of the filter media definea volume into which emboli may flow through the second end when theperiphery is moved away from the elongated member. The emboli aretrapped within the volume when the periphery is radially moved towardthe elongated member. An actuator moves the periphery radially towardand away from the elongated member. The actuator includes a plurality ofelastic loops. The loops are biased to an open loop configuration withthe loops urging the periphery radially away from the elongated member.The actuator is adapted to be manipulated by an operator to urge theloops against the bias to a closed position permitting movement of theperiphery radially toward the elongated member without interference fromthe loops.

III. BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side plan schematic view of an emboli filter according tothe present invention being advanced through an artery with a distal endof the filter advanced past an occlusion;

FIG. 2 is the view of FIG. 1 with the filter media shown in an openposition to trap emboli;

FIG. 3 is a side sectional view of a portion of the filter of FIG. 2;

FIG. 4 is a rear and side perspective view of filter media and loopactuator according to the present invention;

FIG. 5 is the view of FIG. 2 with the filter media closed to capturetrapped emboli and with the filter reduced in size to be retracted fromthe artery;

FIG. 6 is a side plan schematic view of an alternative embodiment of anemboli filter according to the present invention with a filter mediashown in an open position to trap emboli; and

FIG. 7 is a perspective view of another emboli filter constructed inaccordance with the principles of the present invention.

IV. DESCRIPTION OF THE PREFERRED EMBODIMENT

With reference to the various drawing figures a description of apreferred embodiment of the present invention will now be provided. Inthe drawings, similar elements are numbered similarly throughout. Inalternate embodiments, similar elements are similarly numbered with theaddition of a distinguishing apostrophe to distinguish embodiments.Unless modified, such similar elements need not be described more thanonce. While the present invention could be used in a wide variety ofbody lumens (with the apparatus of the invention sized with respect tosuch lumens), the preferred embodiment will be described with referenceto an emboli filter for use in a carotid artery.

With initial reference to FIGS. 1-5, an emboli filter 10 is showndeployed in a carotid artery CA having an internal lumen LU partiallyblocked by an occlusion OC. Blood flow is in the direction of arrow BFin FIG. 1. In FIG. 1, the occlusion OC is shown only partially blockingthe lumen LU such that blood flows through lumen LU and through the gapGA of the occlusion OC.

The filter 10 includes a flexible, elongated member 12 having a distalend 14 and a proximal end 16. In the embodiment of FIGS. 1-5, theelongated member 12 is shown as a solid wire/mandrel. Of course, theelongated member 12 could also be a tube. A flexible, hollow tube 38 ismounted over the elongated member 12. The hollow tube 38 is adapted toslide longitudinally relative to the elongated member. An enlargedcollar 37 forms a distal end 39 of the hollow tube 38. A proximal end 41of the hollow tube 38 is preferably positioned adjacent to the proximalend 16 of the elongated member 12. In certain embodiments, handles canbe attached to one or both of the proximal ends 16 and 41 for allowing aphysician to better manipulate the filter 10. For example, a handle 20is shown attached to the proximal end 16 of the elongated member 12.

The filter 10 also includes a filter media 22 connected to the elongatedmember 12 adjacent the distal end 14. In a deployed state (shown in FIG.2), the filter media 22 has a conical shape coaxial with the elongatedmember 12. A closed conical tip 24 is secured to the elongated member12. Proximal to conical tip 24, the filter media 22 has a peripheryconical base 26.

Opposing surfaces of the filter media 22 define an internal volume 28(FIG. 3). When the filter media 22 is in the open position (FIGS. 2, 3,4 and 7), the periphery 26 is spaced from the elongated member 12.Therefore, blood laden with emboli can flow into the volume 28. Thefilter media 22 is porous or mesh construction such that blood flowsthrough the filter media 22 with emboli being trapped with volume 28.After a therapy period, the filter media 22 is moved to a closedposition (FIG. 5), with the periphery 26 drawn toward the elongatedmember 12 such that the emboli are captured in the closed volume 28.

The filter media 22 is flaccid and is held open by loops 30. Each ofloops 30 is preferably identical. Three loops 30 are shown in FIGS. 2-4.More or fewer could be used. The loops 30 are formed of flexibleresilient material. A suitable material may be nitinol (a well-knownnickel-titanium alloy) or other metal or polymer. Ends 32 (FIG. 3) ofthe loops 30 are secured to the elongated member 12 with the loops 30circumferentially spaced about the elongated member 12.

The loops 30 present a cloverleaf-shape such that the loops 30 have asecondary loop 34 at the top of each loop 30. The secondary loops 34 area convenient attachment location for securing the loops 30 to theperiphery 26 by sutures 36 or any other suitable fastening or adheringmeans. The cloverleaf-shape also provides a good balance of radial forceagainst the artery CA.

The loops 30 are resiliently biased to open radially outwardly such thatthe loops are open in a plane perpendicular to the elongated member 12when the loops 30 are in an open configuration. Each loop 30 isresiliently flexible independent of a remainder of the loops 30.Therefore, in an open configuration, the loops 30 can readilyaccommodate a non-circular interior diameter.

The loops 30 are movable against their bias to a closed configurationwith the loops against the elongated member 12. When so moved, the loops30 draw the periphery 26 toward the elongated member 12 to the closedposition of FIGS. 1 and 5. When in the closed position of FIGS. 1 and 5,the periphery 26 of the filter media 22 is housed or contained withinthe collar 37. Thus, the collar 37 prevents the periphery 26 fromexpanding radially outward. The filter media 22 is opened and closed bylongitudinally sliding the elongated member 12 and the tube 38 relativeto one another. For example, when the tube 38 is held stationary whilethe elongated member is pulled proximally, the collar 37 urges the loops30 against their bias from the open loop configuration toward the closedloop configuration. By contrast, the periphery 26 of the filter media 22can be released from the collar 37 by holding the tube 38 stationarywhile pushing the elongated member in a distal direction.

In the closed state (FIGS. 1 and 5), the emboli filter 10 is sized topass through gap GA to position the filter media 22 distal to anobstruction OC. Typically, the filter 10 will be positioned by insertingthe distal tip 14 in a blood vessel through an incision, and then bymanipulating the proximal end 16 to advance the tip 14 through thevasculature to the occlusion OC. Preferably, during the insertionprocess, the outer tube 38 and the elongated member 12 are movedtogether as one unit. Once the filter media 22 is positioned distal tothe obstruction OC, the physician pushes the elongated member 12distally relative to the collar to release loops 30 and open the filtermedia 22 (FIG. 2). Though desirable, the periphery 26 of the filtermedia 22 need not fully seat against the interior wall of the carotidartery CA. Fluid flow at the wall is turbulent and most emboli arecarried in blood flow closer to the center of the lumen LU. Preferably,a distal portion 15 of the elongated member 12 is highly flexible toavoid trauma as the filter 10 is advanced.

After the filter media 22 is opened, the tube 38 can be removed from theelongated member 12 and a balloon angioplasty device can be slid overthe member 12 and used to compress the occlusion OC against the lumenwall to provide an enlarged gap GA′. Thereafter, a stent 50 can be usedto maintain the enlarged gap GA′. Such treatment may release emboliwhich are captured in the filter volume 28 while blood is permitted topass through the filter media 22. When the therapy is complete, the tube38 is re-inserted over the elongated member 12, and the elongated member12 is pulled proximally relative to the collar 37 of the tube 38 toclose the filter media 22. By closing the filter media 22, emboli arecaptured in the closed volume 28 and the size of the filter 22 isreduced so it can be pulled through the enlarged gap GA′ (FIG. 5) andout of the carotid artery CA.

As described above, the filter media 22 is opened and closed by movingelongated member 12 distally and proximally relative to the tube 38 (andthe attached collar 37). Alternatively, the filter media can be openedand closed by moving the tube 38 distally and proximally, respectively,relative to the elongated member 12. Further, the tube 38 and theelongated member 12 can also be concurrently moved in oppositedirections to open and close the filter media 22.

FIG. 6 shows an alternative embodiment 10′ having loops 30′ that are notcloverleaf-shaped. Instead, the loops 30′ have proximal ends 32′ anddistal ends 33′. The distal ends 33′ are secured to an elongated member12′ by an attachment hub 35′. The proximal ends 32′ are attached to anouter tube 38′. Flexible tie strings 40′ are secured to a periphery 26′of a filter media 22′, and also to the tube 38′.

As tube 38′ is moved proximally relative to the elongated member 12′,the tube 38′ urges the loops 30′ to a closed configuration and ties 40′simultaneously pull on the periphery 26′ to urge the filter media 22′ tobe closed. Distal movement of elongated member 12′ relative to the tube38′ results in the loops 30′ being in the open configuration of FIG. 6with the filter open. Again, as in the previous embodiment, the loops30′ present an open volume 28′ perpendicular to the elongated member 12′so as not to interfere with blood flow. As shown in FIG. 6, theelongated member 12′ has a proximal end 16′ and an enlarged distal tip14′.

FIG. 7 shows another emboli filter 10″ constructed in accordance withthe principles of the present invention. The filter 10″ has the sameconstruction as the filter 10 of FIGS. 1-5, except the loops 30 havebeen replaced with loops 30″ that do not include secondary loops 34. Theloops 30 interconnect an outer filter media 22 to an elongated member12. A collar 37 (i.e., a sheath) is provided for retracting orcollapsing the filter media 22. It will be appreciated that the loops30″ serve the same function as the loops 30, and the filter 10″ operatesin the same manner previously described with respect to the filter 10 ofFIGS. 1-5.

From the foregoing, the present invention has been disclosed in apreferred embodiment. It is intended that modifications and equivalentsof the disclosed concepts, such as those which readily occur to one ofskill in the art shall be included within the scope of the claimsappended hereto.

What is claimed is:
 1. An emboli filter for deployment in a body lumen,said emboli filter comprising: a flexible elongated member sized to bepassed through said lumen, said elongated member having a distal end anda proximal end; a filter media carried on and substantially surroundingsaid elongated member, said filter media having a first end and a secondend, said first end secured to said elongated member adjacent saiddistal end, said second end having a periphery movable toward and awayfrom said elongated member, opposing internal surfaces of said filtermedia defining a volume into which emboli may flow through said secondend when said periphery is moved away from said elongated member, saidemboli trapped within said volume when said periphery is moved towardsaid elongated member; an actuator for selectively moving said peripherytoward and away from said elongated member, said actuator including aplurality of elastic loops, each of said loops having a first end and asecond end, each of said first and second ends being attached to saidelongated member, said first end being attached adjacent to said secondend, said loops biased to an open loop configuration with said loopsurging said periphery away from said elongated member, said actuatoradapted to be manipulated by an operator to urge said loops against saidbias to a closed position permitting movement of said periphery towardsaid elongated member without interference from said loops.
 2. A filteraccording to claim 1 wherein each of said loops is attached to saidperiphery at individual ones of a plurality of attachment locationsspaced apart on said periphery and with said attachment locationsdrawing said periphery toward said elongated member as said loops aremoved to said closed position.
 3. A filter according to claim 1 whereinsaid loops are open in a plane substantially perpendicular to saidelongated member when said loops are biased to said open loopconfiguration.
 4. A filter according to claim 1 wherein each of saidloops is resiliently flexible independent of a remainder of said loops.5. A filter according to claim 1 wherein said filter media issubstantially flaccid and held open only by said loops in said open loopconfiguration.
 6. A filter according to claim 2 wherein each of saidloops includes a secondary loop at said attachment locations.
 7. Afilter according to claim 1 wherein said actuator includes a movablecollar movable axially relative to said elongated member, relativemovement of said collar toward said distal end causing said loops to beurged to said closed position.
 8. A filter according to claim 1 whereinsaid elongated member is hollow throughout a length of said elongatedmember.
 9. A filter according to claim 1 wherein said periphery isoverlying said loops and said periphery is secured to said elongatedmember proximal to said loops by a flexible tie.
 10. A filter accordingto claim 1, further comprising a tube mounted over the elongated member,the tube and the elongated member being longitudinally moveable relativeto one another.
 11. An emboli filter for deployment in a body lumen,said emboli filter comprising: a flexible elongated member sized to bepassed through said lumen, said elongated member having a distal end anda proximal end; a filter media carried on and substantially surroundingsaid elongated member, said filter media having a first end and a secondend, said first end secured to said elongated member adjacent saiddistal end, said second end having a periphery movable toward and awayfrom said elongated member, opposing internal surfaces of said filtermedia defining a volume into which emboli may flow through said secondend when said periphery is moved away from said elongated member, saidemboli trapped within said volume when said periphery is moved towardsaid elongated member; an actuator for selectively moving said peripherytoward and away from said elongated member, said actuator including aplurality of elastic loops, each of said loops having a first end, asecond end, and a looped portion therebetween, said loops biased to anopen loop configuration with said loops urging said periphery away fromsaid elongated member, said actuator adapted to be manipulated by anoperator to urge said loops against said bias to a closed positionpermitting movement of said periphery toward said elongated memberwithout interference from said loops.
 12. A filter according to claim11, further comprising a tube mounted over the elongated member, thetube and the elongated member being longitudinally moveable relative toone another.
 13. A filter according to claim 12, wherein the first endof each of the elastic loops is connected to the tube and the second endof each of the elastic loops is connected to the elongated member.
 14. Afilter according to claim 13, further comprising tie members thatconnect the periphery of the filter media to the tube.
 15. An embolifilter for deployment in a body lumen, said emboli filter comprising: aflexible elongated member sized to be passed through said lumen, saidelongated member having a distal end and a proximal end; a filter mediacarried on and substantially surrounding said elongated member, saidfilter media having a first end and a second end, said first end securedto said elongated member adjacent said distal end, said second endhaving a periphery movable toward and away from said elongated member,opposing internal surfaces of said filter media defining a volume intowhich emboli may flow through said second end when said periphery ismoved away from said elongated member, said emboli trapped within saidvolume when said periphery is moved toward said elongated member; anactuator for selectively moving said periphery toward and way from saidelongated member, said actuator including a plurality of elastic loops,said loops biased to an open loop configuration with said loops urgingsaid periphery away from said elongated member, said loops beingattached to said periphery at individual ones of a plurality ofattachment locations spaced apart on said periphery, said loopsincluding a secondary loop at said attachment locations and with saidattachment locations drawing said periphery toward said elongated memberas said loops are moved to said closed position, said actuator adaptedto be manipulated by an operator to urge said loops against said bias toa closed position permitting movement of said periphery toward saidelongated member without interference from said loops.
 16. An embolifilter for deployment in a body lumen, said emboli filter comprising: aflexible elongated member sized to be passed through said lumen, saidelongated member having a distal end and a proximal end; a filter mediacarried on and substantially surrounding said elongated member, saidfilter media having a first end and a second end, said first end securedto said elongated member adjacent said distal end, said second endhaving a periphery movable toward and away from said elongated member,opposing internal surfaces of said filter media defining a volume intowhich emboli may flow through said second end when said periphery ismoved away from said elongated member, said emboli trapped within saidvolume when said periphery is moved toward said elongated member; anactuator for selectively moving said periphery toward and away from saidelongated member, said actuator including a plurality of elastic loops,each loop including a primary loop and a secondary loop, said loopsbiased to an open loop configuration with said primary loops urging saidperiphery away from said elongated member, said actuator adapted to bemanipulated by an operator to urge said loops against said bias to aclosed position permitting movement of said periphery toward saidelongated member without interference from said loops.
 17. A filterassembly according to claim 16, further comprising means for attachingthe secondary loops to the filter media.
 18. An emboli filter fordeployment in a body lumen, said emboli filter comprising: a flexibleelongated member sized to be passed through said lumen, said elongatedmember having a distal end and a proximal end; a filter media carried onand substantially surrounding said elongated member, said filter mediahaving a first end and a second end, said first end secured to saidelongated member adjacent said distal end, said second end having aperiphery movable toward and away from said elongated member, opposinginternal surfaces of said filter media defining a volume into whichemboli may flow through said second end when said periphery is movedaway from said elongated member, said emboli trapped within said volumewhen said periphery is moved toward said elongated member; an actuatorfor selectively moving said periphery toward and away from saidelongated member, said actuator including a plurality of elastic loops,each of said loops having a first end and a second end, said first andsecond ends being attached to said elongated member adjacent to saidsecond end of said filter media, said loops biased to an open loopconfiguration with said loops urging said periphery away from saidelongated member, said actuator adapted to be manipulated by an operatorto urge said loops against said bias to a closed position permittingmovement of said periphery toward said elongated member withoutinterference from said loops.